[Innovative Self-Powered Design] This revolutionary bicycle tail light operates through electromagnetic induction technology, eliminating the need for batteries or charging. It automatically illuminates during your ride, with brightness increasing as your speed rises. [Enhanced Safety Features] Featuring 2 ultra-bright LED lamps for maximum visibility. The faster you ride, the brighter the light shines - perfect for night cycling safety. High-quality engineering plastic construction ensures durability. [Universal and Weatherproof] - Dimensions: 53mm × 19mm × 32mm (compact and lightweight) - Waterproof design withstands all weather conditions - Flexible installation: fits both horizontal and vertical positions - Compatible with round and flat spoke wheels [Convenience Redefined] - Zero maintenance (no battery replacement needed) - Adds minimal weight to your bike - Easy installation on seat tubes - Ideal for commuters and cycling enthusiasts Upgrade your bike safety with this eco-friendly, maintenance-free tail light that keeps you visible day and night!